Immunization rates for recommended childhood vaccines have consistently been high, with childhood series completion near 80% by 19-35 months. However, these high immunization coverage rates do not fully account for delays or refusals of early childhood (i.e., less than one year of age) vaccine uptake. Overall, the proportion of children not receiving all recommended vaccines or whose parents are consistently limiting visit-level vaccine administration is increasing. Children who do not receive all recommended vaccines are at greater risk of contracting vaccine-preventable diseases, which can lead to development of severe sequelae, hospitalizations, and death. Additionally, despite evidence showing the effect of vaccinating pregnant women in reducing disease among infants too young to be fully vaccinated, maternal immunization rates remain low. We developed and pilot tested a novel, innovative, evidence based, and comprehensive immunization intervention at the Practice, Provider, and Patient (P3) levels to meet the diverse and complex information needs of mothers. This P3 intervention included components such as use of practice-level vaccine champions, expanded reminder-recall systems, and provision of practice-level immunization rate feedback (practice-level interventions); physician peer-delivered training related to vaccines, vaccine-preventable diseases, vaccination recommendations, and vaccination system logistics, as well as standardized talking points for use when recommendation vaccination (provider-level interventions); and an interactive tablet computer (iPad) education application for pregnant women to view while waiting for care (patient-level intervention). Our pilot testing found this P3 intervention to be well received by providers and patients and indicated a few areas where the intervention could be improved. In the proposed project, we will develop and evaluate an improved version of the P3 intervention, to be called P3+. Improvements to the initial P3 framework will be based on findings from the original evaluation project as well as additional formative research. We will then evaluate the P3+ intervention in a geographically and socio-demographically diverse set of obstetrician- gynecologist offices in Georgia (community-level practices) and Colorado (offices of the Kaiser Permanente Colorado managed care organization). The research will be led by Multiple PIs who have extensive experienced in understanding and addressing barriers to vaccine uptake. The proposed evaluation will address vaccine uptake both for pregnant women and for their children, through 24 months of age, to test the hypothesis that increasing acceptability of vaccines during pregnancy will lead to positive changes in acceptance of vaccines for children.